Underwater acoustic sources are useful in the marine environment both near the surface and undersea. For example, acoustic sources can be used to mark the location of an object for salvage, as navigational aids for undersea vehicles, and for other applications.
Current underwater acoustical sources are discrete devices that are dropped from ships or aircraft, intended to sink to a location where they begin transmitting.
S. V. Egerev describes development of noncontact laser acoustic sources in “In Search of a Noncontact Underwater Acoustic Source”, Acoustical Physics, vol. 49, issue 1, pages 51-61, 2003. A laser-based ultrasonic and hypersonic sound generator is discussed in U.S. Pat. No. 3,392,368 to Brewer et al. Laser induced electric breakdown in water is discussed by C. A. Sacchi in the Journal of the Optical Society of America B, Vol. 8, No. 2, February 1991, pages 337-345. P. K. Kennedy discusses laser induced breakdown thresholds in ocular and aqueous media in IEEE Journal of Quantum Mechanics, Vol. 31, No. 12, December 1995, pages 2241-2249 and 2250-2257. A. Vogel and S. Busch discuss shock wave emission and cavitation generation by picosecond and nanosecond optical breakdown in water in J. Acoustical Society of America, Vol. 100, Issue 1, July 1996, pages 148-165.
T. G. Jones, J. Grun, L. D. Bibee, C. Manka, A. Landsberg, and D. Tam discuss laser-generated shocks and bubbles as laboratory-scale models of underwater explosions in Shock and Vibration, IOP Press, Vol. 10, pages 147-157, 2003.
P. Sprangle, J. R. Penano, and B. Hafizi discuss propagation of intense short laser pulses in the atmosphere in Physical Review E, Vol. 66, 2002, pages 046418-1-046418-21. The optical Kerr effect, a non-linear change in the refractive effect at high intensity, is discussed by Siegman, Lasers, pages 375-386, 1986.